Editing Module:Val/units/doc (section)

== Introduction ==
An entry defining a [[Unit of measurement|unit]] for Val is a single line under a [[Wikipedia:section|section]] heading.<ref>Module pages don't have section editing.</ref> It starts with the '''unit code''', followed by at least two spaces and a [[WP:wikilink|link]].  If you are adding a group of related units, you can enter a blank line around them to group them in the report at Val/list. An entry is ignored if it lacks at least ''two adjacent space characters''.  

:<code>''code''{{spaces|4}}[<nowiki/>[ ''pagename'' | ''symbol'' ]]</code>

;unit code
: The keyboard typeable name of the symbol that users give Val's {{para|u}}, {{para|ul}}, {{para|up}} or {{para|upl}} parameters.
* Unit codes will be case sensitive.
* Prefer {{code|u}} for the Greek letter &mu;, if you're not sure.
* Composite units have [[Dimensional analysis#Definition|dimensions]] that multiply, divide, and apply powers to component units.  Use {{code|.}} to multiply, {{code|/}} to divide, and a signed digit for powers.  For multiplication, {{code|*}} is deprecated.  When adding a unit that includes division, consider also adding a version with multiplication by the negated power; for example, {{code|m/s2}} and {{code|m.s-2}} (for <code>m/s<sup>2</sup></code> and <code>m&sdot;s<sup>−2</sup></code>).

;unit pagename
:Title or section of an article. When linked with ul or upl,  the title or one of its [[WP:redirect|redirect]]s can expand the abbreviation for the unit.<ref>A redirect page is easy to make; there are tools on the editor toolbars.</ref>  

;unit symbol
:[[wp:V|Verifiable]], standard symbol, formatted in accordance with [[WP:UNITS]].
* Templates will not work for producing the unit symbol for input to this module; only [[Wikipedia:HTML#Formatting|Wikipedia HTML formatting]] is accepted.
* Composite units use {{code|&sdot;}} to multiply, {{code|/}} to divide, and {{tag|sup}} for powers. Division is also the unit-inversion form that multiplies a negative numbered power, for example for <code>m/s<sup>2</sup></code> and <code>m&sdot;s<sup>−2</sup></code> (from {{code|m.s-2}} and {{code|m/s2}}).
* If the hover-text just shows the abbreviation, it is not a user-friendly unit-symbol. When not linked, the unit's abbreviation can be spelled out with hover-text at the symbol by way of the ''title'' attribute of either {{tag|abbr}} or {{tag|span}}.
* For more about HTML tags and HTML symbols such as {{code|&sdot;}}, see [[Wikipedia:HTML]]. 
* For more information about marking up your unit symbol see [[WP:HTML#formatting]].
* Examples of unit codes, and hover text are at [[Template:Val/list]].

;unit code alias
: The same unit/pagename/symbol, but by way of a different unit code.  
:Unit code aliases are commonly applied for
* capitalization, to make the unit code case insensitive.
* per units, for example <code>m/s</code> and <code>m⋅s{{sup|−1}}</code>.
* Greek letters, to allow for both US keyboard and Greek-character-input applications, for example the SI prefix &mu;

;Preview page with this template/module
: A feature, similar to a sandbox and testcases, that provides a preview of how the code currently in the edit box (sandbox) will look when applied to any page (testcases).

The preview of main interest is {{elc|Template:Val/list}}<ref>The special relation between Val/units and Val/list is that the wikitext of Val/list is always generated by Val/units when that page is viewed, ''so'' when you '''preview page with this module''', Val/list is generated using the contents of the edit box of Val/units.</ref>, but previewing other your own page of interest with your newly added unit in a val call and in a sorting table are also part of this procedure.